The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
The disclosed technology relates to communication systems, and more particularly, to performing successive interference cancellation (SIC) in multiple input multiple output (MIMO) systems.
In a data transmission system, it is desirable for information, often grouped into packets, to be accurately received at a destination. A transmitter at or near the source sends the information provided by the source via a signal or signal vector. A receiver at or near the destination processes the signal sent by the transmitter. The medium, or media, between the transmitter and receiver, through which the information is sent, may corrupt the signal such that the receiver is unable to correctly reconstruct the transmitted information. Therefore, given a transmission medium, sufficient reliability is obtained through careful design of the transmitter and/or receiver, and of their respective components.
Successive interference cancellation (SIC) is one technique for improving the performance of a data transmission system. According to this technique, a received codeword that is associated with strong channel conditions is decoded before other codewords that are associated with weak channel conditions. Effects of the decoded codeword are subtracted from a received signal vector to eliminate interference due to the decoded codeword from the other codewords. In this way, the other codewords may experience less interference and are able to achieve a higher Signal-to-Noise Ratio (SNR) than without interference cancellation.
The order in which codewords are decoded may have an important impact on the SIC performance. Conventional SIC methods decode codewords in an order that is based on channel parameters (e.g., channel quality) associated with each codeword. These conventional approaches provide a locally optimal decoding order because such approaches select, at each decoding stage, a best codeword for that stage. Furthermore, these approaches operate on the assumption of perfect interference cancellation, which is not always true. However, a codeword that is locally optimal at a given decoding stage may not guarantee the largest interference cancellation gain for the remaining codewords.